1. Field of the Invention
The present invention relates to an authentication system, an authentication apparatus, an authentication target apparatus, an authentication method, a method of being authenticated, a program for realizing those on a computer, and a computer-readable information recording medium for recording the program.
Particularly, the present invention relates to an authentication system, an authentication apparatus, an authentication target apparatus, an authentication method, and a method of being authenticated which are suitable for authenticating an authentication target apparatus by comparing a position of the authentication target apparatus estimated by observing a radio wave from a common radio star at a common observation time, with the real position of the authentication target apparatus, and a program for realizing those, and a computer-readable information recording medium for storing this program.
2. Description of the Related Art
Conventionally, in the field of information communication technologies, authentication techniques for confirming who is the message creator or message sender have been researched. Nowadays, signature authentication systems and encryption communication systems using public key encryption are becoming widespread.
In the meantime, attempts have been made to receive radio waves radiated from radio stars such as quasars, and maser radio sources (including water maser radio source, ammonia maser radio source, and methanol maser radio source) using a VLBI (Very Long Baseline Interferometry) and utilize the received radio waves in various technical fields. There are advantages that signals received by a VLBI have ideal complete randomness, and that radio waves from radio stars can be received at every point on the earth (note that radio waves from some kinds of radio stars can be received at every point as long as the point exists on a surface facing toward the radio stars).
Therefore, techniques using a VLBI for measuring a relative positional relation between a point and another point on the earth are gradually put into practical use.
However, in the field of information communication technologies, a more secure authentication technique that can prevent “pretending” is required. Especially, in today's situation where information are exchanged over the boarders so often, more security is required for secret information sent to the Japanese government and Japanese companies from overseas.